An experimental program for measuring the fraction of liquid entrained in the gas stream through a horizontal 3-inch pipe has been conducted. A customized test section was designed and fabricated for this testing, including an isokinetic sampling system designed for pressures up to 3,600 psi to measure the liquid entrained in the gas phase. Two sets of tests were conducted one with an oil-nitrogen mixture and another with oil-methane. During the testing, the pressure was varied between 500 psig and 1,200 psig. The superficial gas velocity was varied between 2 m/s and 17 m/s, while the superficial liquid velocities varied from 0.005 m/s to 0.1 m/s. Flow visualization at high-pressure was also conducted to verify the flow pattern at high-pressure.
In gas-liquid streams in pipes, the two phases adopt various geometrical distributions known as flow patterns. The flow pattern depends on operational (gas and liquid flow rates), geometrical (such as pipe diameter and inclination angle), and physical properties of the two phases (i.e., density, viscosity, surface tension).1
In horizontal gas-liquid two-phase flow, several flow patterns can be observed. In liquid-dominated systems flow patterns can range from stratified, to slug flow, to dispersed bubble flow. The focus of this study is on gas-dominated systems where flow patterns range from stratified, to wavy, to annular flow.
In two-phase flow, liquid entrainment refers to the amount of liquid carried by a continuous gas phase in the form of droplets. In horizontal pipes, it occurs primarily in gas-dominated systems with stratified-wavy and annular flow patterns.
In gas-dominated two-phase flows, the atomization of droplets, due to the effect of the gas on the gas/liquid interface, is thought to be accompanied by a deposition process where droplets redeposit on the liquid film. The atomization of droplets depends primarily on the fluid properties of the gas and liquid phases (density, viscosity, and surface tension) and on the gas and liquid velocities. Droplet deposition depends on the droplet size and concentration, and on the gas core turbulence 2,3.